How can I CamelCase-enable Vim Search
nnoremap <expr> <leader>/ SearchCamelCase('/')
nnoremap <expr> <leader>? SearchCamelCase('?')
function! SearchCamelCase(dir)
    call inputsave()
    let ab = input(a:dir)
    call inputrestore()
    let l = filter(split(toupper(ab), 'zs'), 'v:val =~ "\w"')
    if len(l) > 0
        let l[0] = '[' . l[0] . tolower(l[0]) . ']'
    end
    let @/ = 'C<' . join(map(l, 'v:val . "[0-9a-z_]*"'), '') . '>'
    return a:dir . "r"
endfunction